Field of Invention
The present invention is related to an integrated circuit element, and more generally to a test key.
Description of Related Art
In a semiconductor fabrication, a semiconductor device or an integrated circuit is continuously tested in every step so as to maintain the device or circuit quality. Normally, a testing circuit is simultaneously fabricated with an actual device so that the quality of the actual device is judged by the performance of the testing circuit. The quality of the actual device is therefore well controlled. A wafer acceptance test (WAT) is frequently employed to detect defects on a wafer. The WAT method includes testing several test keys distributed on scribe lines between dies. Various test keys for detecting different defects are developed.